Every year, around 50 people in the UK die of Legionnaires' disease, an infection caused by inhaling water droplets infected with the Legionella bacterium. The pathogen occurs in water between the temperatures of 20-45°C and is transmitted via fine sprays, e.g. from a shower head or fountain, etc. This programme outlines the symptoms of Legionnaires' disease and states the groups most vulnerable to infection, however its main focus is upon the conditions that allow the Legionella bacterium to survive in water supplies and the prevention of these conditions. NHS guidance on controlling Legionella is discussed, covering inspections, maintenance and temperature regulation. However, the impact of flow rates upon the survival of Legionella in water systems may currently be underestimated.

The programme advises designers and contractors what to consider when specifying and installing water systems such as spray taps, shower units and toilet flushing systems. It also focuses on the Legionnaires' outbreak of 2002 at the Barrow-in-Furness Arts Centre, including the legal consequences for the architect.